Have you ever wondered about the difference between gloss medium and matte medium?

Exciting news! I’ve been chosen as one of 68 artists for the West Bend, WI Main Street Artwalk banner project and today I am learning about how to apply a gloss medium to a gesso surface.  The gesso surface I laid down to the banner canvas is very rough, has an almost sand texture.  I want my paint to flow and blend nicely.  But do I use gloss medium or matte medium and what is the difference?  Michele Th├ęberge from The Mindful Artist explains it very well on this youtube link!